Lubricating grease thickened with ultramarine blue



United States Patent IJUBRICATING GREASET-HICIENED WITH ULTRAMARINE'BLUE" I PP e l ,.,aud Norm an R. I nae"; FishkmtNiY-i ers-"to Texacolne, a cor- P li9uofDelaware Noni-mung App i nmaugust 13, 1957 Serial No. 677,823

5 Claims. (Cl. 252-28) 'r ivinvention -relatesto lubricating greases thickened with ultramarine blue in finely *divided form.

Ultramarine blue is a-double silicate of aluminum and alkali metal -containingfchemically combined sulfur, which is produced commercially by heating together clay, sodium carbonate and/ or sodium sulfate, sulfur and a-jcarbonaceous material suchas charcoal, pitch or rosin, either with" or without added silica, at temperatures of about-11500? F.-for twenty-four hourso'r longer. It ordinarily comprises about 35 to about 50 percent by weight ofsilicat, about-2010 about 32 percent by weight of -alumina,about-l8 to ab'out'23 percent by weight of, alkali metal oxide, and at least about 1 percent by weight of;=sulfur. The preferred materials of this character for use"-in'; accordance with the-present invention are those containing about 6 to about 14 percent by: weight-of sulfur.

We have found that lubrieating rgreases'of improved extreme pressure properties and other advantages are obtained by dispersing"finely"divided Ultramarine blue in lubrieatin'g oils in suitable proportions. The extreme pressure properties of these greases are substantially in excess of those obtained with .other non-organic solid thickeners which have been employed as grease thickening agents heretofore, and 'are"apparently-due to the sulfur which the ultramarine blue contains.

The lubricating greasesof this invention comprise an oleaginous liquid vehicle and a grease forming proportion of ultramarine blue in finely divided form, suitably in the form of particles below about 5.0 microns in diameter, and preferably from about 0.05 to about 3.0 microns in diameter. The amount of ultramarine blue employed will usually range from about 5 percent to about 45 percent by weight of the grease, and very advantageously from about percent to about 40 percent by weight of the grease.

The oleaginous liquid vehicle employed in these greases may be any oleaginous liquid suitable for use in grease making generally, such as mineral lubricating oils obtained by any of the conventional refining processes, preferably refined mineral oils in the viscosity range from about 100 to 600 seconds Saybolt Universal at 100 F. Other oleaginous materials which may be used are vegetable oils such as corn oil, cottonseed oil, castor oil, etc., and animal oils such as lard oil, sperm oil, etc. For some purposes, as for preparing greases for high temperature operations, various synthetic oils may be employed with particular advantage, such as, for example, polyalkylene glycols, various high molecular weight esters and ethers, and silicone polymer oils.

The lubricating greases are prepared without the necessity for any special equipment by merely mixing together the oleaginous liquid vehicle and the ultramarine blue in finely divided form, employing any convenient means for obtaining a uniform dispersion of the solid thickener in the oleaginous liquid. A colloid mill or a mill of the type employed to grind paint pigments may be empolyed very advantageously for this purpose. The mixing may material, or corresponding approximately 'tothe fonnula Na Al Si -.4S '0 It-wasemployed iii-the form of particles having a particle'size mostly within the range 0.1-0.5, microns diameter'with a minor proportion-of larger particles having diameters up to about 3.0 microns; and having a measured surface area of 20 square meters per gram. The grease was prepared by stirring" the two ingredients together and passing themixturethrou gh a Premier Colloid Mill with two passesat-0.002 inchclearance. A soft blue grease of'exc ellenttexture and appearance was obtained having .the following properties:

Dropping point, F. 500+ A.S.T.M. Working Stability Test: 7

A.S.T.M. Penetration at 77 F.

Worked 60 strokes 3'43 I Worked 100,000 strokes M 360 A.S.T.M. Bomb Oxidation Test, hrs. at"2l0'F.':

Pressure drop, lbs. 6

As shown by the data given above, the grease represen tative of the greases of this inventionhada high droppingpoint, good shear stability and high oxidation resistance without the use of'inhibitors. Table- [below shows the extreme pressure properties of agrease of the composi tion described above in comparison with those of'a' grease of approximately the same grade obtained' byemploying finely divided silica as the thickening agentinamineral lubricating oil of the same type.

Table I Grease N o. 1 2

Thickening Agent Sllica.... Ultramarine Blue. Mean Hertz Load, Seizure load, Kg. 29 Four Ball Navy Wear, Mlcrons/mlnute 13.2"... 9.4 Tuzuken, 0.K. Test, lbs 1 14..--- 20 1 Obtained upon a grease of approidmately the same grade prepared from a different mineral oil.

The above tests are well known laboratory tests for determining the extreme pressure and antiwear properties of lubricants. The Mean Hertz Load and Navy Wear tests are carried out as described, for example, in U.S. 2,600,056, column 12, lines 13-60, employing a test machine which comprises four steel balls in a pyramid arrangement and lubricated at their points of contact with the lubricant under test. The test comprises rotating the upper ball at a high speed in contact with the other three balls, while a load is applied to the system by means of a lever arm. The Mean Hertz Load is the load upon the lever which causes welding after 10 seconds of operation. The Navy Wear values represent the average diameter of the score marks upon the balls after one minute with a weight of 10 kilograms upon the lever arm. The T imken OK test is carried out employing the test machine described in U.S. 1,990,771. It consists essentially in rotating :1 flat steel ring against a steel test block wire while the area of contact is lubricated with the lubricant under test, and applying increasing loads by five pound increments until welding occurs. The load just before the load which causes welding is the OK load.

As shown by the data in Table I, both the extreme pressure and antiwear properties of the ultramarine blue thickened grease were considerably superior to those of the silica thickened grease, which are typical of the results which have been obtained heretofore by employing inorganic solids as thickening agents in greases. The extreme pressure properties of the ultramarine blue thickened grease were also much superior to those of the conventional soap thickened greases, which ordinarily have Mean Hertz loads in about the range 20 to 25 and Tirnken OK values of about 10.

In addition to the ultramarine blue thickener, the

greases of this invention may contain the conventional fatty acid soaps as additional thickening agents. For example, about 5 to 15 percent by weight of ultramarine blue may be added very advantageously to a grease containing about to 30 percent by weight of a sodium, calcium, aluminum, or mixed base soap of stearic acid or other long chain fatty acid or hydroxy fatty acid. A superior block grease is obtained by mixing about 10 to percent by weight of this material with a grease containing about to percent by weight of a sodium or mixed sodium-calcium soap in a heavy or residual type mineral lubricating oil.

. Additives of the usual type employed in lubricating greases, such as oxidation inhibitors, corrosion inhibitors and tackiness agents, such as various high polymer materials, extreme pressure agents, etc. may also be present. As examples of particularly suitable corrosion or rust inhibitors may be mentioned metal salts of wax benzene sulfonates, metal salts of petroleum sulfonate, lauryl phosphate, sorbitol monooleate and glycerol monostearate. Suitable oxidation inhibitors include phenyl-alpha-naphthylamine, diphenyl-para-phenylenediamine, tetramethyldiaminodiphenylmethane and bis (Z-hydroxy-B-t-butyl-S- methylphenyl) methane.

With particular advantage, a surface active agent, such as a quaternary ammonium salt of a fatty acid, a polyglycol ether, a metal alkyl sulfate or sulfonate, etc., may be employed in these greases in order to improve their water resistance and emulsification characteristics. The surface active agent may be added in any suitable man- 4 ner during the preparation of the grease. Very advantageously, such a compound may be employed to treat the ultramarine blue before the latter is combined with the oleaginous liquid vehicle.

Obviously, many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A lubricating grease comprising a lubricating oil as the predominating constituent, and about 5 to percent by weight, based on the weight of the grease, of Ultramarine blue in finely divided form, having a particle size from about 0.05 to about 3.0 microns in diameter.

2. The composition according to claim 1, wherein the ultramarine blue consists essentially of 35 to percent by weight of silica, 20 to 32 percent by weight of alumina, 18 to 23 percent by weight of alkali metal oxide and 6 to 14 percent by weight of sulfur.

' 3. The composition according to claim 1, wherein the ultramarine blue is a material of the approximate formula Na Al Si 4S O 4. The composition according to claim 1, wherein the said lubricating oil is a mineral lubricating oil having a viscosity in the range from about to 600 seconds SU at 100 F.

5. A lubricating grease consisting essentially of a major portion of a mineral lubricating oil thickened to a grease consistency by about 20 to 40 percent by weight, based on the weight of the grease, of finely divided ultramarine blue having a particle size in the range of about 0.05 to 3.0 microns.

References Cited in the file of this patent UNITED STATES PATENTS 1,431,079 Acheson Oct. 3, 1922 2,020,539 Dourif Nov. 12, 1935 2,648,633 Peterson et al. Aug. 11, 1953 OTHER REFERENCES Transactions, Faraday Society, London, vol. 36 pp. 1007-17 (1940) Articles by Mardles. 

1. A LUBRICATING GREASE COMPRISING A LUBRICATING OIL AS THE PREDOMINATING CONSTITUENT, AND ABOUT 5 TO 45 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF THE GREASE, OF ULTRAMARINE BLUE IN FINELY DIVIDED FORM, HAVING A PARTICLE SIZE FROM ABOUT 0.05 TO ABOUT 3.0 MICRONS IN DIAMETER. 